1. Field of the Invention
This invention relates to an apparatus for successively forming slide fastener coupling elements by transversely cutting a blank wire of a generally Y-shape cross section with repeated rolling, and more particularly to a slide fastener coupling element forming apparatus equipped with a preventing means for preventing with reliableness a freshly formed coupling element from jumping up obliquely from a cutting punch during cutting.
2. Description of the Related Art
Conventional slide fastener coupling element forming methods of the described type are chiefly divided into two groups: one in which generally Y-shape coupling elements are formed by successively punching a continuous length of flat belt-shape metal plate and, at the same time, bulges for successive coupling heads are formed one at a time (the resulting coupling elements will be hereinafter called "metal-plate coupling elements"); and the other in which individual coupling element blanks are obtained by threading a continuous length of blank wire through a plurality of rollers to shape it into a generally Y shape in cross section and then by successively cutting it into slices of a predetermined thickness using a coacting cutting punch and die, whereupon a bulge is formed at the individual coupling head of the coupling element using by a coacting bulge forming punch and die (the resulting coupling elements will be hereinafter called "wire coupling elements"). The former conventional method is exemplified by Japanese Utility Model Publication No. Sho 62-16886, and the latter conventional method is exemplified by Japanese Patent Publication No. Sho. 59-27667, corresponding to U.S. Pat. No. 4,388,751. Subsequently, the coupling elements obtained by either conventional method are individually collected loose, or are successively attached to a fastener tape on the same apparatus.
In forming the coupling elements from a blank wire, since the wire coupling elements formed in a generally Y-shape cross section is successively cut into slices of a predetermined thickness perpendicularly to the blank wire, the freshly formed coupling elements are smooth at their entire surfaces giving an excellent appearance, and it is possible to achieve a very high rate of production with no loss of material. This method is therefore most suitable for forming coupling elements.
However, according to the conventional method of forming wire coupling elements, when the blank wire having a Y-shape cross section is projected from the upper surface of the cutting die by a length corresponding to the thickness of a single coupling element as the blank wire is intermittently supplied through the insertion hole of the cutting die, the cutting die starts moving backwardly so that the projected length of blank wire is cut by a bifurcated blade of the cutting punch fixed to, for example, a frame, holding from opposite side surfaces at the root of cutting length. Then the cut coupling element is moved to the forming die where a bulge is formed on a head portion of the coupling element. The resulting coupling elements are individually collected from the forming die or are attached successively to the fastener tape continuously supplied at a predetermined pitch.
In the conventional method of wire coupling elements, when the blank wire is cut by the cutting punch as the cutting die moved backwardly, the cut coupling element held its opposite sides by the bifurcated blade tends to jump up obliquely forwardly from the blade of the cutting punch. If it is thus jumped up from the blade, the coupling element cannot be neatly received in the mold of the forming die not only so that desired forming is difficult to achieve but also that such coupling elements cannot be attached at a uniform pitch. This might damage peripheral equipments.